首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   2351553篇
  免费   186984篇
  国内免费   4515篇
耳鼻咽喉   31960篇
儿科学   79185篇
妇产科学   66917篇
基础医学   337616篇
口腔科学   68936篇
临床医学   211071篇
内科学   454911篇
皮肤病学   51589篇
神经病学   190332篇
特种医学   92599篇
外国民族医学   753篇
外科学   354772篇
综合类   58014篇
现状与发展   3篇
一般理论   903篇
预防医学   184656篇
眼科学   54276篇
药学   174653篇
  6篇
中国医学   4462篇
肿瘤学   125438篇
  2018年   23090篇
  2016年   20289篇
  2015年   23214篇
  2014年   31939篇
  2013年   49042篇
  2012年   65518篇
  2011年   69360篇
  2010年   41288篇
  2009年   39216篇
  2008年   65923篇
  2007年   69640篇
  2006年   70701篇
  2005年   68471篇
  2004年   67166篇
  2003年   64430篇
  2002年   62795篇
  2001年   108115篇
  2000年   111643篇
  1999年   94416篇
  1998年   26374篇
  1997年   24002篇
  1996年   23763篇
  1995年   23151篇
  1994年   21731篇
  1993年   20448篇
  1992年   77421篇
  1991年   75503篇
  1990年   74206篇
  1989年   71574篇
  1988年   66034篇
  1987年   65616篇
  1986年   61945篇
  1985年   59937篇
  1984年   45083篇
  1983年   38590篇
  1982年   22914篇
  1981年   20586篇
  1980年   19263篇
  1979年   42679篇
  1978年   30098篇
  1977年   25406篇
  1976年   23940篇
  1975年   25157篇
  1974年   30787篇
  1973年   29646篇
  1972年   27215篇
  1971年   25658篇
  1970年   23620篇
  1969年   22125篇
  1968年   20301篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Evidence continues to grow on potential environmental health hazards associated with engineered nanomaterials (ENMs). While the geno- and cytotoxic effects of ENMs have been investigated, their potential to target the epigenome remains largely unknown. The aim of this study is two-fold: 1) determining whether or not industry relevant ENMs can affect the epigenome in vivo and 2) validating a recently developed in vitro epigenetic screening platform for inhaled ENMs. Laser printer-emitted engineered nanoparticles (PEPs) released from nano-enabled toners during consumer use and copper oxide (CuO) were chosen since these particles induced significant epigenetic changes in a recent in vitro companion study. In this study, the epigenetic alterations in lung tissue, alveolar macrophages and peripheral blood from intratracheally instilled mice were evaluated. The methylation of global DNA and transposable elements (TEs), the expression of the DNA methylation machinery and TEs, in addition to general toxicological effects in the lung were assessed. CuO exhibited higher cell-damaging potential to the lung, while PEPs showed a greater ability to target the epigenome. Alterations in the methylation status of global DNA and TEs, and expression of TEs and DNA machinery in mouse lung were observed after exposure to CuO and PEPs. Additionally, epigenetic changes were detected in the peripheral blood after PEPs exposure. Altogether, CuO and PEPs can induce epigenetic alterations in a mouse experimental model, which in turn confirms that the recently developed in vitro epigenetic platform using macrophage and epithelial cell lines can be successfully utilized in the epigenetic screening of ENMs.  相似文献   
82.
83.
84.
A 17‐year‐old boy presented with recurring severe dermatitis of the face of 5‐months duration that resembled impetigo. He had been treated with several courses of antibiotics without improvement. Biopsy showed changes consistent with allergic contact dermatitis and patch testing later revealed sensitization to benzoyl peroxide, which the patient had been using for the treatment of acne vulgaris.  相似文献   
85.
86.
Abstract

Objective: To understand the origin of extremely high gonadotropin levels in a perimenopausal woman.

Methods: A 52-year-old woman with a 2?months of amenorrhea followed spontaneous menstrual cycles recovery was referred to our outpatient clinic with elevated follicle-stimulating hormone (FSH, 483 mUI/ml), luteinizing hormone (LH, 475 mUI/ml) and prolactin (PRL, 173?ng/ml). She was known to take levosulpiride. The gonadotropin levels did not fit with the clinical features.

Results: A gonadotroph tumor was ruled out. Further analysis confirmed constantly high FSH, LH and PRL levels. The measurements were repeated using different analytical platforms with different results. After serial dilutions, nonlinearity was present suggesting an immunoassay interference. After post-polyethylene glycol recovery, hormone levels appeared in the normal range. Anti-goat antibodies were recognized in the serum of the patient.

Conclusions: This case report shows a case of falsely abnormal high gonadotropin and PRL levels in a woman during menopause transition. In the clinical practice the evaluation of gonadotropin profile is not recommended at this age, but the abnormal levels stimulated further evaluation. An interference in the assay due to anti-goat antibodies resulted in abnormally high level of FSH and LH. A strict collaboration between clinicians and the laboratory is needed, when laboratory findings do not correspond to clinical findings.  相似文献   
87.
88.
89.
90.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号